Place barley in a medium saucepan. Cover with cold water by 1-1/2 inches. Cover, and let stand at room temperature for 8-12 hours.
When ready to begin cooking, place stock in a small saucepan over medium heat, and bring to a simmer. (Don’t boil.) Drain barley, spread on a clean kitchen towel, and blot dry.
Heat 1 tablespoon oil in a large heavy saucepan over medium heat. Add shallot and a pinch of salt, and cook 2 minutes, or until tender, stirring occasionally. Add barley, and cook 2 minutes, stirring constantly. Add wine, and cook 3 minutes, until wine is absorbed. Add 3 cups warm stock, and bring to a boil. Reduce heat, and cook at a low boil for 12-15 minutes, stirring occasionally, until the barley is tender and creamy.
While barley cooks, heat remaining 1 teaspoon oil in a skillet over medium heat. Add prosciutto, and cook 5 minutes, or until crispy. Remove prosciutto from pan with a slotted spoon, and drain on a paper towel. Raise heat to medium. Add peas and remaining 1/2 cup warm stock to pan for 5 minutes, or until peas are tender and stock evaporates.
Stir peas and grated cheese into barley. Season to taste with salt and pepper. Serve garnished with prosciutto and shaved cheese.